Color television tube



u my l948 A, c` scHRol-:DER 2,446,791

COLOR TELEVISION TUBE Filed June 1l, 1946 FAG. 2

A ORNEY Patented ug. l0, i948 UNlTED 'ras rm NT FPlCE coma TELEVISIONTUBE Alfred C. Schroeder, Feasterville, Pa., assignor to RadioCorporation of America, a corporation of Delaware a plurality ofconductors, the potentials of which are adapted to be varied fordirecting the electrons of the beam successively onto the red, green andblue strips.

Other objects will appear in the following specification, referencebeing had to the drawings, in which:

Figure 1 is a diagrammatic illustration of a part of a screen and gridembodying the invention.

Figure 2 is a modied form of screen.

My improvement will be rst described in connection with a pick-uptransmitting tube, such as the well-known iconoscope.

In Fig. 1 of the drawing, the target or screen consists of a transparentbody l, such as the glass of the end of the evacuated tube envelope, orit may be a separate sheet of glass or mica inserted therein. Positionedin front of the screen is a grid comprising a plurality of wires 2,alternate ones of which are connected to conductors 3 and d. These wireswould be connected to the conductors :at the sides of the screen, but inthe diagrammatic illustration the connection has been shown between thewires and screen for Y convenience of illustration. On the base I isplaced a plurality of color lines or sections extending from one side ofthe screen to the other. These color sections are the same size as thediameter of the wires, which is preferably the same size as the spacingbetween the wires. With this arrangement there is a color section orstrip directly opposite each wire and each space. These color strips mayconsist of materials of diierent sensitivity to light, such that lightfrom a red portion of :an object being televised, for example, causesthe most plhotoelectrons to be emitted, that from a green object lessphotoelectrons and that from a blue object still less photoelectrons.Alternatively, the material may have uniform sensitivity to light of therepresentative colors and the quantity of light' varied by placing ltersin front of the sections. The strips opposite the spaces between theWires are all adapted to produce the same color signal, red by way ofexample. The strips directly opposite the wires are alternately ofdifferent colors, say green and blue. The color arrangement, of course,may be made in any other order.

A unit 5, Shown diagrammatically in the drawing, is adapted to place a.plurality of potentials on the conductors 3 and li. The changes inpotential are produced in synchronism with the frame scanning frequencyof the pick-up tube. The scanning means, both at the transmitter and thereceiver, may be of the usual type and are not shown. During one framescansion of the pickup tube the conductors 3 and 4 will have the samepotential and the beam electrons will pass through the spaces betweenthe wires and strike the red sections 1' on the screen. This isillustrated at A of Fig. l. These sections will therefore producesignals proportional to the red light of the image for one entirescansion, as the beam shifts its line scansion from top to bottom of thescreen. The wires 2 will prevent the electrons from striking the greenand blue color strips, because they are directly behind the wires. Thus,during this entire scansion, when the wires have the same potential,nothing but red signals will be transmitted.

In the next frame scansion, the condition is illustrated at B. Duringthis scansion the potentials are placed on the conductors 3 and il suchthat 3 is positive with respect to The field produced between the gridand screen thus deects the electrons so that they strike the greensections only. This relation of potentials is maintained for onecomplete frame and therefore, as the beam scans the screen from top tobottom, green signals will be picked up for this entire scansion.

In the next scansion, potentials are placed on the conductors such thatconductor 3 is negative to conductor The result of this change ofpotentials upon the landing of electrons is illustratecl at C in Fig. 1.The electrons passing between the wires are deiiected so as to strikethe blue sections only and this relation will be maintained throughoutone complete scansion. Thus, blue signals will be picked up andtransmitted.

Instead of making the sections of photo-sensitive material of differentsensitivity to light of di'erent colors, I may place iilter strips 6 onthe body l in any way, for example by putting dyes of appropriate coloron the body, as indicated in Fig. 2. This may be done either on theoutside or inside of the tube end I, but I have illustrated it on thebeam side. Then, one may deposit over the surface of the red, green andblue lter sections a photo-sensitive material 'l that is uniformlysensitive to color. The colors of the lters and also the grid wires andtheir connection to the unit. will be arranged in exactly the same wayas illustrated in Fig. 1, but these have not been illustrated as theoperation of Fig. 2 will be clear from the previous di scription of Fig.1.

When my improved target and grid arrange- ,ment is to be used forconverting picked up signais into pictures, the color sections of thescreen S may consist of different phosphor materials, the r sectionshaving a phosphor that emits red light under impact of electrons, the bsections a phosphor that emits blue light under similar impact and the gsections one that emits green light under the impact of electrons.Alternatively, the screen may be made as shown in Fig. 2, but for thereceiving kinescope tube the mosaic 1 will be made of a phosphormaterial producing substantially white light and the strips in thecolumn 6 would consist of red, green and blue filters, as alreadydescribed.

In producing pictures, the received signals will be brought into areceiving set and will be, after amplification, applied to the grid inthe gun of the kinescope in the usual fashion. The potentials betweenconductors 3 and 4 are varied in the same way as at the pick-up tube insynchronism therewith. Therefore, when a red signal is picked up at thetransmitting tube and is received in the usual way, not shown, thepotential on conductors 3 and 4 will be identical and the phosphormaterial struck by the electrons passing between the wires will emit itsred color. which will be viewed through the body I, say the end of thetube. When green signals are received, as at B, conductor 3 will have agreater potential than conductor 4 and for this frame scansion greensignals only will be produced. During the next frame scansion, when bluesignals are received, conductor 4 will have greater potential thanconductor 3 and only the phosphor emitting blue light will be struck bythe electrons passing between the wires. In this Way, one viewing theimage through the end of the tube i will view in succession rod, greenand blue images. which blend together to produce the colored picture.

While I have shown arrangements for producing three colors, theinvention is not limited thereto, as different numbers of colors may beproduced. For example, by merely alternating the potential of theconductors 3 and 4 and omitting the step in which they have equalpotential, a two-color picture may be produced.

Various other modifications may be made without departing from thespirit of the invention.

I claim:

1. In pick-up tubes having a gun for scanning a cathode ray beam over ascreen. a grid having parallel wires joined together, another gridhaving parallel wires joined together, the wires of one grid alternatingWith those of the other with uniform spacing between the wires, a screenin a plane parallel with and adjacent to said grids, a plurality ofcolor strips on said screen parallel to the wires of the grids, thecolor strips opposite the spaces between the wires having maximumsensitivity to red light, the color strips opposite the wires of onegrid having maximum sensi'- tivity to green light and those opposite thewires of the other grid having maximum sensitivity to blue light andmeans for applying potentials to said grids for causing the beamelectrons passing between the grid wires to land on the red, green andblue strips in succession.

2. In pick-up tubes having a gun for scanning a cathode ray beam over ascreen, a grid having parallel wires Joined together, another gridhaving parallel wires joined together, the wires of one grid alternatingwith those of the other with uniform spacing between the wires, a screenin a plane parallel with and adjacent to said grids, a plurality ofcolor strips on said screen parallel to the wires of the grids, thecolor strips opposite the spaces between the wires having maximumsensitivity to light of one color, the color strips opposite the wiresof one grid having maximum sensitivity to light of another color andthose opposite the wires of the other grid having maximum sensitivity tolight of a different color, and means for applying potentials to saidgrids for causing the beam electrons passing between the grid wires toland on the strips opposite the spaces. the wires of one grid and thewires of the second grid in succession.

3. In pick-up tubes having a gun for scanning a cathode ray beam over ascreen, a grid having parallel wires joined together, another gridhaving parallel vwires joined together, the wires of one gridalternating with those of the other with uniform spacing between thewires, a screen in a plane parallel with and adjacent to said grids, aplurality of color strips on said screen parallel to the wires of thegrids, the color strips opposite the spaces between the wires respondingto light of one color, the color strips opposite the wires of one gridresponding to light of another color and those opposite the wires of theother grid responding to light of a different color, and means forapplying potentials to said grids for causing the beam electrons passingbetween the grid wires to land on the strips opposite the' spaces, thewires of one grid and the wires of the second grid in succession.

4. In pick-up tubes having a gun for scanning a cathode ray beam over ascreen, a grid having parallel wires joined together, another gridhaving parallel wires joined together, the wires of one grid alternatingwith those of the other with uniform spacing between the wires, a screenin a plane parallel with and adjacent to said grids, and a plurality ofcolor strips on said screen parallel to the wires of the grids, thecolor strips opposite the spaces between the wires having maximumsensitivity to red light, the color strips opposite the wires of onegrid having maximum sensitivity to green light and those opposite thewires of the other grid having maximum sensitivity to blue light.

5. In pick-up tubes having a gun for scanning a cathode ray beam over ascreen, a grid having parallel wires `oined together, another gridhaving parallel Wires joined together, the wires of one grid alternatingwith those of the other with uniform spacing between the wires, a screenin a plane parallel with and adjacent to said grids, and a plurality ofcolor strips on said screen parallel to the wires of the grids, thecolor strips opposite the spaces between the wires having maximumsensitivity to light of one color, the color strips opposite the wiresof one grid having maximum sensitivity to light of another color andthose opposite the wires of the other grid having maximum sensitivity tolight of a different color.

6. In pick-up tubes having a gun for scanning a cathode ray beam over ascreen, a grid having parallel Wires joined together, another grid hav-5 ing parallel wires joined together, .the wires of one grid alternatingwith those of the other with uniform spacing between the wires, a screenin a plane parallel with and adjacent to said grids, and a plurality ofcolor strips on said screen parallel to the wires of the grids, thecolor strips opposite the spaces between the wires responding to lightof one color, the color strips opposite the wires of one grid respondingto light of another color and those opposite the wires of the other gridresponding to light of a different color.

7. In television reproducing tubes having a gun for scanning a cathoderay beam over a screen, a grid having parallel wires joined together,another grid having parallel wires joined together, the wires of onegrid alternating with those of the other with uniform spacing betweenthe wires, a screen in a plane parallel with and adjacent to said grids,a plurality of color strips on said screen parallel to the wires of thegrids, the color strips opposite the spaces between the wires adapted toproduce red light, the color strips opposite the wires of one gridadapted to produce green light and those opposite the wires of the othergrid adapted to produce blue light, and means for applying potentials tosaid grids for causing the beam electrons passing between the grid wiresto land on the red, green and blue strips in succession.

8. In television reproducing tubes having a gun for scanning a cathoderay beam over a screen, a grid having parallel wires joined together,another grid having parallel wires joined together, the wires of onegrid alternating with those of the other with uniform spacing betweenthe wires, a screen in a plane parallel with and adjacent to said grids,a plurality of color strips on said screen parallel to the wires of thegrids, the color strips opposite the spaces between the wires adapted toproduce light of one color, the color strips opposite the wires of onegrid adapted to produce light of another color and those opposite thewires of the other grid adapted to produce light of a different color,and means for applying potentials to said grids for causing the beamelectrons passing between the grid wires to land on the strips oppositethe spaces, the wires of one grid and the wires of the second grid insuccession.

9. In television reproducing tubes having a gun for scanning a cathoderay beam over a screen, a grid having parallel wires joined together,another grid having parallel wires joined together, the wires of onegrid alternating with those of the other with uniform spacing betweenthe wires, a screen in a plane parallel with and adjacent to said grids,a plurality of color lter strips on said screen parallel to the wires ofthe grids, the lter strips opposite the spaces be-v tween the wiresadapted to produce light of one colorl the filter strips opposite thewires of one grid adapted to produce light of another color and thoseopposite the wires of the other grid adapted to produce light of adifferent color, phosphor materia1 on said iter strips and means forapplying potentials to said grids for causing the beam electrons passingbetween the grid wires to land on the phosphor material on said i'llterstrips opposite the spaces, the wires of one grid and the wires of thesecond grid in succession.

10. In television reproducing tubes having a gun for scanning a cathoderay beam over a screen. a grid having parallel wires joined together,another grid having parallel wires joined together, the wires of onegrid alternating with those of the other with uniform spacing betweenthe wires, a phosphor screen in a plane parallel with and adjacent to said grids, and a plurality of color filter strips on said screenparallel to the wires of the grids, the lter strips opposite the spacesbetween the wires adapted to pass red light, the filter strips oppositethe wires of one grid adapted to pass green light and those opposite thewires of the other grid adapted to pass blue light.

11. In television reproducing tubes having a gun for scanning a cathoderay beam over a screen, a grid having parallel wires joined together,another grid having parallel wires joined together, the'wires of onegrid alternating with those of the other with uniform spacing betweenthe Wires, a phosphor screen in a plane parallel with and adjacent tosaid grids, and a plurality of filter strips on said screen parallel tothe wires of the grids, the filter strips opposite the spaces betweenthe wires adapted to pass light of one color, the iilter strips oppositethe wires of one grid adapted to pass light of another color and thoseopposite the wires of the other grid adapted to pass light of adifferent color.

12. In television reproducing tubes having a gun for scanning a cathoderay beam over a screen, a grid having parallel wires joined together,another grid having parallel wires joined together, the wires of onegrid alternating with those of the other with uniform spacing betweenthe wires, a phosphor screen in a plane parallel with and adjacent tosaid grids, and a plurality of strips on said screen parallel to thewires of the grids adapted to produce colored light, the strips oppositethe spaces between the wires adapted to produce red light, the stripsopposite the wires of one grid adapted to produce green light and thoseopposite the wires of the other grid adapted to produce blue light.

13. In television reproducing tubes having a gun for scanning a cathoderay beam over a screen, a grid having parallel wires joined together,another grid having parallel wires joined together, the wires of onegrid alternating with those of the other with uniform spacing betweenthe wires, a phosphor screen in a plane parallel with and adjacent tosaid grids, and a plurality of strips on said screen parallel to thewires of the grids adapted to produce colored light, the strips oppositethe spaces between the wires adapted to produce light of one color, thestrips opposite the wires of one grid adapted to produce light ofanother color and those opposite the wires of the other grid adapted toproduce light of a different color.

14. In television reproducing tubes having a gun for scanning a cathoderay beam over a screen, a grid having parallel wires joined together,another grid having parallel wires joined together, the wires of onegrid alternating with those of the other with uniform spacing betweenthe wires, a screen in a plane parallel with and adjacent to said grids,and a plurality of phosphor strips on said screen parallel to the wiresof the grids, the strips opposite the spaces between the wires adaptedto produce light of one color, the strips opposite the wires of one gridadapted to produce light of another color and those opposite the wiresof the other grid adapted to produce light of a different color.

ALFRED C. SCHROEDER.

